Apparatus for treating spinal stenosis

ABSTRACT

A device for treating spinal stenosis having an implant body structure sized and configured to be positioned between the spinous processes of two adjacent vertebrae. The device may have a body portion having a first end portion, a second end portion and a sleeve between the first and second end portions. The device may also have at least two retainers positioned in and extendable from the body portion. A mechanism positioned within the body portion may be used to move the retainers between a retracted position and a deployed position. When the retainers are in the deployed position, the retainers may be positioned around the spinous process of at least one of two adjacent vertebrae. A plurality of installation tools may be used to install the device.

TECHNICAL FIELD

The present invention relates to an apparatus and method for stabilizingthe human spine and, more specifically, to an implant for insertionbetween adjacent vertebrae.

BACKGROUND

A human vertebrae has a rearwardly projecting portion known as a spinousprocess. Bending of the spine can cause the spinous processes ofadjacent vertebrae to be moved toward each other. This constricts thespace in the spinal canal and foramina and, thus, may cause pain. Suchconstriction, which is known as stenosis, can be treated by the use ofan implant in the space between adjacent spinous processes.

Some current implants are made of separate pieces which requireinsertion from opposite sides of the spine and in a posterior approachand necessitate rather wide openings into a patient, cutting both leftand right thoracolumbar fascia as well as stripping the multifidusmuscles from their attachments. It is desirable to provide an implantfor insertion between the spinous processes of adjacent vertebrae whichcan be inserted through a single opening in a minimal invasive approachand may be held firmly in position between the vertebrae.

SUMMARY

The device of the present invention may include a body portion having afirst end portion, a second end portion and a sleeve which may bepositioned between the first and second end portions. The device may besized and configured to fit between the spinous processes of twoadjacent vertebrae. The sleeve may be a single piece of material or maycomprise multiple components which may be made of materials havingdifferent properties (e.g., different modulus of elasticity). The devicemay have at least two retainers, which may be positioned within the bodyportion and may move between a deployed position and a retractedposition. The device may also have a connector which may join the firstand second end portions.

An actuation tool (e.g., a screwdriver) may be used to rotate theconnector. Rotation of the connector may move the first and second endportions towards each other. As the first and second end portions aremoved toward each other, the retainers may be deployed from the device.In the deployed position, the retainers may extend outward from the bodyportion and may be positioned on opposite sides of at least one spinousprocess of a vertebrae. In a preferred embodiment, the device may havefour retainers for engaging opposite sides of two spinous processes ofadjacent vertebrae. Such retainers may hold the implant relative to thespine.

In an alternative embodiment, the device includes a body portion havinga first end portion, a second end portion and a sleeve which may bepositioned between the first and second end portions. The first endportion may have an elongated member extending therefrom and two or moreretainers may be operably associated with the first end portion andelongated member. In a preferred embodiment, two retainers may bepivotably connected to the first end portion and two retainers may bepivotally connected to the elongated member. A connector may bepositioned between the end portions such that rotation of the connectormay draw the end portions together. The second end portion may have oneor more opening through which a retainer may pass. As the end portionsmove together, the retainers connected to the elongated member may movethrough the opening in the second end portion and extend away from thebody portion. Moreover, the retainers connected to the first end portionmay move against the sleeve and extend away from the body portion. Thebody portion and first and second end portions may be situated such thatspinous processes of adjacent vertebrae may be positioned between theretainers. In another embodiment, at least one retainer, but preferablytwo retainers may be pivotably connected to each end portion. As the endportions move together, the retainers may move against the sleeve andmay extend from the body portion.

In one method of inserting the spinous spacer, an incision may be madein the side of a patient. A guide wire may be inserted through theincision and in between adjacent spinous process. An extension may beoperably connected to the guide wire to extend the length of the wire. Adilator may be inserted over the guide wire and may retract tissue anddistract the spinous processes. Thereafter, sequentially larger tubesmay be positioned over the dilator, further dilating tissue anddistracting adjacent spinous processes. Once the largest tube is inposition, the guide wire, dilator and any other smaller tubes may beremoved from the body. An implant holder may be attached to the spinousspacer in an expanded configuration and may be used to insert the devicedown the tube in between the vertebrae. An actuation tool may bepositioned through the implant holder and may engage the connector. Theimplant holder may be held stationary while the actuation tool may berotated. In this way, the end portions of the spinous spacer may movetowards each other and the retainers may deploy from the body portionand through slots in the tube. Once the retainers are deployed and thedevice is positioned between adjacent spinous processes, the implantholder, actuation tool and outer tube may be removed from the body.

BRIEF DESCRIPTION OF THE DRAWINGS

The spinous spacer and the method of use and insertion are explained ineven greater detail in the following exemplary drawings. The spinousspacer, and its method of operation and use may be better understood byreference to the following drawings, wherein like references numeralsrepresent like elements. The drawings are merely exemplary to illustratethe structure, operation and method of use of the spinous spacer andcertain features that may be used singularly or in combination withother features and the invention should not be limited to theembodiments shown.

FIG. 1 is a side view of an exemplary embodiment of an implant of thepresent invention positioned between adjacent spinous processes;

FIG. 2 is a perspective view of an exemplary embodiment of the implantof FIG. 1 in a first configuration;

FIG. 3 is a perspective view of an exemplary embodiment of the implantof FIG. 1 in a second configuration;

FIG. 4 is a side view of an exemplary embodiment of a retainer of theimplant of FIG. 1;

FIG. 5 is a top view of an exemplary embodiment of the retainer of FIG.4 along line 5-5;

FIG. 6 is an end view an exemplary embodiment of the retainer of FIG. 4;

FIG. 7 is a side view showing a partial cross-section of the implant ofFIG. 2;

FIG. 7A is a perspective view of an exemplary embodiment of analternative implant of the present invention;

FIG. 7B is a side view showing a partial cross-section of the implant ofFIG. 7A;

FIG. 7C is a perspective view of an exemplary embodiment of anotheralternative implant of the present invention;

FIG. 7D is a side view showing a partial cross-section of the implant ofFIG. 7C;

FIG. 8 is a side view of the implant of FIG. 7 along line 8-8;

FIG. 9 is a side view showing a partial cross-section of the implant ofFIG. 2 with certain portions of the implant not illustrated;

FIG. 10 is a cross-sectional view of an exemplary embodiment of an endportion of the implant of FIG. 2;

FIG. 11 is a cross-sectional view of the end portion of FIG. 10 alongline 11-11;

FIG. 12 is a side view of an exemplary embodiment of an inner portion ofthe implant of FIG. 2;

FIG. 13 is an end view of the inner portion of FIG. 12 along line 13-13;

FIG. 14 is a cross-sectional view of the inner portion of FIG. 12 alongline 14-14;

FIG. 15 is a top view of an exemplary embodiment of a pair of retainersof FIG. 4;

FIG. 16 is a partial cross-sectional view of the implant of FIG. 2;

FIG. 17 is another cross-sectional view of the implant of FIG. 2;

FIG. 18 is a side view of an exemplary actuation mechanism as shown inFIG. 7;

FIG. 19 is a cross-sectional view of an exemplary sleeve of the implantof FIG. 2;

FIG. 20 is a cross-sectional view of the end portion of FIG. 10;

FIG. 21 is a cross-sectional view of the end portion of FIG. 20 alongline 21-21;

FIG. 22 is a side view of an exemplary embodiment of an implant holderof the present invention;

FIG. 23 is a partial cross-sectional view of the implant holder of FIG.22 along line 23-23;

FIG. 24 is a side view of an exemplary distal portion of the implantholder of FIG. 22;

FIG. 25 is a partial cross-sectional side view of an exemplaryembodiment of a guide wire of the present invention;

FIG. 26 is a side view of an exemplary embodiment of a guide wire holderof the present invention;

FIG. 27 is a side view of an exemplary embodiment of an extension forthe guide wire FIG. 25;

FIG. 28 is a partial cross-sectional side view of an exemplaryembodiment of a dilator of the present invention;

FIG. 29 is an enlarged, cross-sectional view of a proximal portion of anassembled guide wire of FIG. 25, guide wire extension of FIG. 27, anddilator of FIG. 28;

FIG. 30 is a side view of an exemplary embodiment of an insertion deviceof the present invention;

FIG. 31 is a top view of the insertion device of FIG. 30 along line31-31;

FIG. 32 is a perspective view of the insertion device of FIG. 30;

FIG. 33 is a side view of exemplary embodiment of another insertiondevice of the present invention;

FIG. 34 is a top view of the insertion device of FIG. 33 along line34-34;

FIG. 35 is a perspective view of the insertion device of FIG. 33;

FIG. 36 is a partial side view of an exemplary embodiment of an implantactuation tool of the present invention;

FIG. 37 is a side view of an exemplary embodiment of an implant removaltool of the present invention;

FIG. 38 is a side view of an exemplary embodiment of an alternativeimplant in a first configuration;

FIG. 39 is a top view of the implant of FIG. 38 along line 39-39;

FIG. 40 is a perspective view of the implant of FIG. 38 in a secondconfiguration;

FIG. 41 is a side view of an exemplary embodiment of another alternativeimplant of the present invention; and

FIGS. 42-44 are cross-sectional views of alternative exemplaryembodiments of the sleeves of the implants of FIGS. 2, 40 and 41.

DESCRIPTION

As shown in FIG. 1, the device 10, referred to herein as a spinousspacer, may include a body portion 12, a first set of retainers 14 and16, and a second set of retainers 18 and 20. The body portion 12 mayhave a sleeve 44, a first end portion 40 and a second end portion 42.The first and second end portion 40, 42 may be moveable relative to thesleeve 44. It should, however, be understood that those of ordinaryskill in the art will recognize many modifications and substitutionswhich may be made to various elements of the present invention.

The device 10 may be positioned in between spinous processes of adjacentvertebrae for treating, for example, spinal stenosis. The spinous spacer10 may be one member of a set/kit of implants 10 which have differentdimensions which takes into account the differing anatomy of patients.Although the device 10 is described herein as being used in connectionwith treating spinal stenosis, one of ordinary skill in the art willreadily appreciate that the device may be used in any other part of thebody, including specifically the spine where occupying space betweenportions of the spine and vertebrae may be desirable. Thus, the locationand/or surgical procedure is not intended to be limiting in any way.

The first end portion 40, second end portion 42 and sleeve 44 may be anyshape, for example, round, oval or polygonal. Moreover, the retainers14, 16, 18 and 20 may be straight, concave, convex or any other shape solong as a vertebral body (e.g. spinous process) may be held be pairs ofretainers 14, 16 and 18, 20. The body portion 12, including the firstand second end portions 40, 42 and sleeve 44, as well as the retainers14, 16, 18 and/or 20 may be made of any suitable material, preferablybiocompatible material, such as metal (e.g., stainless steel, titanium,aluminum, an alloy of two or more metals), plastic, rubber, ceramic,natural body tissue (e.g., bone) or a composite material (i.e., made upof two or more materials). Various factors may be considered whendetermining the material used to make the elements of the device 10,including but not limited to, for example, ability to withstandsterilization, ability to withstand forces exerted thereon, weight,durability, and the ability to grip the device 10, particularly withlatex gloves. With regard to the retainers 14, 16, 18 and 20, factorsmay also include the ability to elastically and plastically bend, and/ordeform the retainers 14, 16, 18 and 20 as well as the ability to retainshape after deformation. The body portion 12 and/or any other componentof the device 10 may be radiolucent or radio-opaque. In embodimentswhere the body portion 12 or other components may be radiolucent,radio-opaque markers (not shown) may be incorporated into or attached tothe body portion 12 or other components. The radio-opaque markers mayassist a surgeon in properly aligning the body portion 12 or othercomponents relative to a patient's anatomy.

The retainers 14, 16, 18 and 20 may be sized and configured similar toeach other and may pass through the sleeve 44, first portion 40 andsecond portion 42. As shown in FIGS. 4-6, each retainer 14, 16, 18 and20 may be an elongated structure such as, for examples, a wire 50. Thewire 50 may have a gauge of between about 0.01 inches and about 0.1inches. Moreover, the wire 50 may have a length of between about 1.0inch and about 10 inches before being formed into retainer 14, 16, 18and 20. The wire 50 may be generally U-shaped with a curved portion 56and arms 52, 54, which may extend from the curved portion 56. The curvedportion 56 may be curved or bent in more than one plane as illustratedin FIGS. 4, 5 and 6. As shown in FIG. 4, the curved portion 56 may havea radius of curvature R1 of, for example, between about 0.1 inches andabout 1.0 inch, more preferably, between about 0.1 inches and about 0.5inches and, most preferably, between about 0.15 inches and about 0.2inches. As shown in FIG. 5, the curved portion 56 may have a radius ofcurvature R2 of, for example, between about 0.01 inches and about 1.0inch, more preferably, between about 0.05 inches and about 0.5 inchesand, most preferably, between about 0.05 inches and about 0.1 inches.

Furthermore, as illustrated in FIGS. 4 and 6, an end 60 of the arm 52may be bent in a first direction at an angle θ (e.g., about 90 degrees)relative to the arm 52. The end 62 of the arm 54 may be bent in a seconddirection, which may be the same or different direction as the firstdirection and which may be at an angle α (e.g., about 90 degrees)relative to the arm 54. In one embodiment, the end 62 may also be bentat an angle Θ (e.g., about 15 degrees) (FIG. 6) towards the arm 52. Theends 60 and 62 may be bent at angles other than about 90 degreesrelative to arms 50, 52, respectively, or may have no bend at all. Endportions 60 and 62 of each retainer 14, 16, 18 and 20 may be operablyconnected to an end portion 40, 42. Moreover, the curved portions 56 ofeach retainer 14, 16, 18 and 20 may be slideably connected to the otherend portion 40, 42.

As shown in FIGS. 7 and 8, the first end portion 40 may comprise an endcap 64 and an inner portion 66, each of which may have a generallycylindrical configuration and which may be centered on the axis 43. Anend 68 of the inner portion 66 may be received in a groove 69 within theend cap 64 so that the inner portion 66 and the end cap 64 may beconnected together. The end 68 may have a conical configuration;however, those skilled in the art will appreciate than another othershape may be used so long as the end 68 may be held in the end cap 64.

As shown in FIGS. 10 and 11, the end cap 64 may have first and secondcam surfaces 70, and first and second teeth 72 proximate the camsurfaces 70. The cam surfaces 70 may have an angle β of, for example,between about 90 degrees and about 160 degrees, more preferably, betweenabout 100 degrees and about 135 degrees and, most preferably, betweenabout 105 degrees and about 115 degrees. The teeth 72 and cam surfaces70 may be located within diametrically opposed openings 73 in the endcap 64.

Moreover, as shown in FIGS. 12, 13 and 14, the inner portion 66 may havea first and second upper slot 76, 78, respectively. A notch 80 at theend of the first upper slot 76 may extend at an angle λ (e.g., about 90degrees) relative to the slot 76 (e.g., a downward angle) and a notch 82at the end of the second upper slot 78 may extends at an angle μ (e.g.,about 15 degrees) relative to the slot 78 (e.g., upward and toward thefirst upper slot 76). The angle of the notch 80 relative to the slots 76may correspond to the angle θ of end 60 of the retainers 14, 16, 18 and20. The angle of the notch 82 relative to the slots 78 may correspond tothe angle Θ of the end 62 of the retainers 14, 16, 18 and 20. The innerportion 66 may also have first and second lower slots 84 and 86, whichmay have notches 88 and 90, respectively. The notch 88 at the end of thefirst lower slot 84 may extend at an angle σ (e.g., about 15 degrees)relative to the slot 84 (e.g., notch 88 may be angled downward and awayfrom the second lower slot 86) and the notch 90 at the end of the lowerslot 86 may extends at an angle ρ (e.g., about 90 degrees) relative tothe slot 86 (e.g., an upward angle). The angle of the notch 88 relativeto the slots 84 may correspond to the angle Θ of the end 62 of theretainers 14, 16, 18 and 20. The angle of the notch 90 relative to theslots 86 may correspond to the angle θ of end 60 of the retainers 14,16, 18 and 20.

As illustrated in FIGS. 15 and 16, at least a portion of the retainers14 and 16 may be positioned beside each other and generally inside thebody portion 12 when in the deployed or undeployed position. As shown inFIG. 16, the arms 52 and 54 of the retainers 14 and 16 may be receivedin the first and second upper slots 76 and 78 in the inner portion 66 ofthe first end portion 40. The ends 60 and 62 (FIG. 17) of the retainer14 may be received in the notches 80 and 82, respectively, at the endsof the first and second upper slots 76 and 78, respectively, of thefirst end portion 40 such that the retainer 14 may be fixed with respectto the first end portion 40. The curved portion 56 of the retainer 16may be positioned adjacent the cam surface 70 (FIG. 7) on the end cap 64of the first end portion 40, and may be positioned around the tooth 72such that the retainer 16 may slide with respect to the end cap 64 ofthe first end portion 40. The arms 52 and 54 of the retainers 14 and 16may also be received in the first and second upper slots 76 and 78 in aninner portion 66 of the second end portion 42. The ends 60 and 62 of theretainer 16 may be received in the notches 80 and 82, respectively, atthe ends of the first and second upper slots 76 and 78, respectively, ofthe second end portion 42 such that the retainer 16 may be fixed withrespect to the second end portion 42. The curved portion 56 of theretainer 14 may be positioned adjacent the cam surface 70 on the end cap64 of the second end portion 42, and may be positioned around the tooth72 such that the retainer 14 may slide with respect to the end cap 64 ofthe second end portion 42.

Similarly, at least a portion of the retainers 18 and 20 may bepositioned beside each other and generally inside the body portion 12when in the deployed or undeployed position. As shown in FIG. 16, thearms 52 and 54 of the retainers 18 and 20 may be received in the firstand second lower slots 84 and 86 in the inner portion 66 of the firstend portion 40. The ends 60 and 62 (FIG. 17) of the retainer 18 may bereceived in the notches 90 and 88, respectively, at the ends of thefirst and second lower slots 86 and 84, respectively, of the first endportion 40 such that the retainer 18 may be fixed with respect to thefirst end portion 40. The curved portion 56 of the retainer 20 may bepositioned adjacent the cam surface 70 (FIG. 7) on the end cap 64 of thefirst end portion 40, and may be positioned around the tooth 72 suchthat the retainer 20 may slide with respect to the end cap 64 of thefirst end portion 40. The arms 52 and 54 of the retainers 18 and 20 mayalso be received in the first and second lower slots 84 and 86 in aninner portion 66 of the second end portion 42. The ends 60 and 62 of theretainer 16 may be received in the notches 90 and 88, respectively, atthe ends of the first and second lower slots 86 and 84, respectively, ofthe second end portion 42 such that the retainer 20 may be fixed withrespect to the second end portion 42. The curved portion 56 of theretainer 18 may be positioned adjacent the cam surface 70 on the end cap64 of the second end portion 42, and may be positioned around the tooth72 such that the retainer 18 may slide with respect to the end cap 64 ofthe second end portion 42.

As shown in FIGS. 7-9, the end cap 64 and inner portion 66 of the secondend portion 42 may be identical to the end cap 64 and inner portion 66of the first end portion 40. Within the body portion 12, the retainers14 and 16 generally may be positioned beside each other. The arms 52 and54 of the retainers 14 and 16 may be received in the first and secondupper slots 76 and 78 in the inner portion 66. The ends 60 and 62 (FIG.17) of the retainer 16 may be received in the notches 80 and 82,respectively, at the ends of the first and second upper slots 76 and 78,respectively. The curved portion 56 of the retainer 14 may be positionedadjacent the cam surface 70 (FIG. 8) on the end cap 64, and may bepositioned around the tooth 72. Similarly, the retainers 18 and 20generally may be positioned beside each other in the body portion 12.The arms 52 and 54 of the retainers 18 and 20 may be received in thefirst and second lower slots 84 and 86 in the inner portion 66. The ends60 and 62 of the retainer 20 may be received in the notches 90 and 88,respectively, at the ends of the first and second lower slots 86 and 84,respectively. The curved portion 56 of the retainer 18 may be positionedadjacent the cam surface 70 on the end cap 64, and may be positionedaround the tooth 72.

A connector 100 may extend along the axis 43 between the end portions 40and 42 of the body portion 12. As shown in FIG. 18, the connector 100may have external screw-threads and may have sections 102, 104. Eachsection 102 and 104 may have a recess 105 for receiving an actuationtool (e.g., actuation tool 184 of FIG. 36). The recess 105 may havegripping surfaces for engaging corresponding gripping surfaces on anactuation tool (e.g., the recess 105 may be polygonal in shape). Thesections 102 and 104 also have respective screw threads 106 and 108which may extend around the connector 100 in opposite directionsrelative to each other (e.g., section 102 may have right handed threads106; section 104 may have left handed threads 108). As shown in FIGS. 7and 9, the screw threads 106 and 108 on the connector 100 may engagecorresponding internal screw threads 114 on the inner portions 66 of endportions 40 and 42 of the body portion 12. Such a configuration mayenable the end portions 40 and 42 to move along the connector 100axially toward each other upon rotation of the connector 100 relative tothe inner portions 66.

When the two end portions 40 and 42 move axially toward each other, theretainers 14, 16, 18 and 20 may move with respect to the end portions40, 42. The retainers 14, 16, 18 and 20 may move with the end caps 64and inner portions 66 to which the ends 60, 62 of the retainers 14, 16,18 and 20 may be attached. As the end portion 40 moves, the retainers 14and 18 which may be fixed in the end cap 64 of the first end portion 40may also move so that the curved portions 56 of the retainers 14 and 18may be pushed forcefully against the cam surfaces 70 on the end cap 64of the second end portion 42. Similarly, as the end portion 42 moves,the retainers 16 and 20 which may be fixed in the end cap 64 of thesecond end portion 42 may also move so that the curved portions 56 ofthe retainers 16 and 20 may be pushed forcefully against the camsurfaces 70 on the end cap 64 of the first end portion 42. The camsurfaces 70 may guide the curved surfaces 56 so that the retainers 16and 20 may move outward through the openings 73 in the end cap 64 of thefirst end portion 40 and the retainers 14 and 18 may move outwardthrough the openings 73 in the end cap 64 of the second end portion 42.More specifically, the arms 52 and 54 of the retainer wires 50 may alsomove outward through the openings 73 as the end portions 40 and 42 ofthe body structure 12 continue to move axially toward each other. Thearms 52 and 54 may be deflected (e.g., along an arcuate or straightpath) as the arms 52 and 54 slide outward against the cam surfaces 70.The retainers 14, 16, 18 and 20 may be pre-bent so that they resume thebent configuration once extended from the ends 40, 42 (e.g., theretainers 14, 16, 18 and 20 may have a shape memory). Alternatively, theretainers 14, 16, 18 and 20 may be deformed (elastically or plastically)as the retainers 14, 16, 18 and 20 move out of the body portion 12. Whenthe retainers 14, 16, 18 and 20 extend out of the end portions 40, 42,the retainers 14, 16, 18 and 20 may be positioned around adjacentspinous processes in the deployed position, and the retainers 14, 16, 18and 20 may help to hold the device in position between adjacent spinousprocesses as shown in FIG. 1. In a deployed position, the retainers 14,16, 18 and 20 may extend away from the body a length L1 (FIG. 1) whichmay be, for example, between about 0.2 inches and 2.0 inches, morepreferably, between about 0.3 inches and 1.0 inch and, most preferably,between about 0.4 inches and about 0.6 inches. Moreover, in a deployedposition, the retainers 14 and 16, 18 and 20 may have a dimension D2(FIG. 1) between adjacent retainers 14 and 16, 18 and 20 which may besubstantially the same as the length L2 of the sleeve 44 (FIG. 19). Thedimension D2 may be at least, for example, between about 0.1 inch and2.0 inches, more preferably, between about 0.2 inches and 1.0 inchesand, most preferably, between about 0.4 inches and about 0.5 inches.Moreover, In addition, retainers 14, 16, 18 and 20 may be retracted intothe body portion 12.

The sleeve 44 may also help to hold the body portion 12 in positionbetween adjacent spinous processes as shown in FIG. 1. In the expandedconfiguration of FIG. 2, the sleeve 44 may be freely movable axially androtationally relative to the other parts of the implant 10 (e.g., theend portions 40, 42 and retainers 14, 16, 18 and 20). In the contractedconfiguration of FIG. 3, the sleeve 44 may be captured between the endportions 40 and 42 and may be prevented from moving axially about axis43. In one embodiment, the sleeve 44 may be fixed with respect to theconnector 100 such that the sleeve 44 may not move axially relative tothe connector 100. The sleeve 44 may, however, be free to rotaterelative to the end portions 40 and 42 as well as the retainers 14, 16,18 and 20. If bending or other movement of the spine causes the spinousprocesses 24 and 26 to impart rotational forces to the sleeve 44, thoseforces may be dissipated by rotation of the sleeve 44 relative to theother parts of the implant 10. Such a construction may prevent thetransmission of rotational forces from the sleeve 44 to the retainers14, 16, 18 and 20 and, thereby, may help prevent unwanted rotationand/or displacement of the retainers 14, 16, 18 and 20.

As shown in FIG. 19, the sleeve 44 may have an outer surface 120 with adiameter D, which may be uniform along the length of the sleeve 44(e.g., the sleeve may have a cylindrical contour). For example, thediameter may be between about 0.1 inches and about 1.0 inches, morepreferably, between about 0.15 inches and about 0.8 inches and, mostpreferably, between about 0.235 inches and about 0.63 inches. As shownin FIG. 8, the end caps 64 of the end portions 40, 42 may have diameterswhich may be substantially similar to the diameter D. An inner surface122 of the sleeve 44 may have a contour (e.g., convex contour) which maybe curved radially outward. The inner surface 122 may define a taperedcentral section 124 of the sleeve 44 which may be thinner than thesections 126 at opposite ends of the sleeve 44. The sleeve may have athickness T, for example, between about 0.01 inches and about 0.15inches, more preferably, between about 0.02 inches and about 0.07 inchesand, most preferably, between about 0.035 inches and about 0.05 inches.Such a construction may provide greater flexibility to the sleeve 44 atthe central section 126 so that the sleeve 44 may be deflected radiallyinward under forces applied from the spinous processes 24 and 26.

It should be noted that in some embodiments, a sleeve 44 may beunnecessary. For example, as shown in FIGS. 7A and 7B, the first endportion 40 may have an extended wall portion 40 a. When the implant isin the contracted configuration, the extended wall 40 a may bepositioned between adjacent spinous processes. In an alternativeembodiment, as shown in FIGS. 7C and 7D, the first end portion 40 andsecond end portion 42 may have extended wall portions 40 a and 42 a,respectively. When the implant is in the contracted configuration, theextended walls portions 40 a, 42 a may be positioned between theadjacent spinous processes.

In use, the body portion 12 may be inserted in the space 23 between thespinous processes 24 and 26 of adjacent vertebrae 28 and 30 (shownschematically). The body portion 12 may have a first, expandedconfiguration such as shown in FIG. 2. In such a configuration, the bodymay have a length L (FIG. 7) of, for example, between about 0.15 inchesand about 5.0 inches, more preferably, between about 0.5 inches andabout 2.0 inches and, most preferably, between about 1.2 inches andabout 1.4 inches. In the first configuration, end portions 40 and 42 ofthe body structure 12 may be spaced apart from each other along alongitudinal central axis 43. The sleeve 44 may be positioned betweenthe end portions 40 and 42. In the expanded configuration, the retainers14, 16 and 18, 20 may be located in a retracted or undeployed positionsuch that the retainers 14, 16 and 18, 20 generally may be positionedwithin the body portion 12. Such a construction may enable the bodyportion to be inserted in between the spinous processes 24 and 26 fromthe side of the spine. Once the spinous spacer 10 is positioned betweenthe spinous processes 24, 26, the body portion 12 may be moved to asecond, contracted configuration such as shown in FIG. 3. To accomplishthis, the end portions 40 and 42 may be moved axially toward each other.In the contracted configuration, the body 12 may have a length L (FIG.7) of, for example, between about 0.05 inches and about 2.0 inches, morepreferably, between about 0.5 inches and about 1.5 inches and, mostpreferably, between about 0.7 inches and about 0.9 inches. As the endportions 40 and 42 move towards each other, the retainers 14, 16, 18 and20 may be moved out of the body 12 from the retracted position to thedeployed position of FIG. 3. In the deployed position, the retainers 14and 16 may extend away from the body portion 12 and may be positioned onopposite sides of the spinous process 24 on the vertebrae 28. Theretainers 18 and 20 may extend away from the body portion 12 and may bepositioned on opposite sides of the spinous process 26 on the vertebrae30. In this arrangement, the body portion 12 may help maintain a desiredspacing between the adjacent spinous processes 24 and 26. Furthermore,the retainers 14, 16, 18 and 20 may help to hold the body portion 12 inplace with respect to the spine and/or surrounding soft tissue.

Various instruments may be used for insertion and/or removal of theimplants 10 such as, for example, an implant holder 140, guide wire 170,dilator 176, insertion tubes 180, 182, actuation tool 184 and removaltool 290. While the instruments described below may be used with theimplant 10, one of ordinary skill in the art will readily appreciatethat any number of instruments may be used in place of those describedherein.

The implant holder 140 of FIGS. 22-24 may include an elongated stem 142and a handle 144. The elongated stem 142 may be hollow (e.g., tubular)and may extend from the handle 144 and has a distal end 143. A wheel 148may be positioned on the handle 144. A shaft 146, which may also behollow, may extend through the stem 142, and may be operably connectedto the wheel 148 so that rotation of the wheel 148 may result inrotation of the shaft 146 relative to the stem 142. As shown in FIG. 24,the distal end 143 of the shaft 146 may protrude from an open end 150 ofthe stem 142 and may have a screw-thread 152. A pair of protrusions 154,which may be diametrically opposed to each other (one of which is shownin FIG. 24), may project axially outward from the open end 150 of thestem 142 proximate the shaft 146. It should be noted that in someembodiments, one or more protrusions 154 may be used.

The implant inserter 140 may engage the first or second end portions 40,42 and may be used as an insertion tool for moving the implant 10 intoits installed position from the side of the spine. As shown in FIGS. 20and 21, the end caps 64 of the first and/or second end portions 40, 42may have a pair of slots 130 at an outer end 132. It should be noted,however, that the end portions 40, 42 may have one or more slots 130,which may be engaged by one or more protrusions 154 of the stem 142.Moreover, the first and/or second end portions 40, 42 may have aninternal screw thread 134 which may extends axially inward from theouter end 132. The screw-thread 152 of the shaft 146 may engage thescrew thread 134 of the first or second end portions 40, 42. Thereafter,the wheel 148 may be rotated to draw the holder 140 and, consequently,the protrusion(s) 154 of the holder 140 towards the first or second endportions 40, 42 so that the protrusion(s) 154 may be inserted into theslot(s) 130 of the first or second end portions 40, 42. The constructionof the end portions 40, 42 and the holder 140 may prevent the endportions 40, 42 and retainers 14, 16 18 and 20 from rotating relative tothe holder 140 about the axis 43.

The spinous spacer 10 may be inserted into the body using, for example,a lateral approach to the spine. An incision may be made in a patient'sside. A guide wire 170, such as shown in FIG. 25, may be insertedthrough the incision. A distal end 194 of the guide wire 170 may besharpened to assist the guide wire 170 in penetrating soft tissue. Aproximal end 190 of the guide wire 170 may have an engagement portionsuch as, for example, an inner screw-threaded counterbore 192. A surgeonmay grasp the guide wire 170 directly or may use a holder 172 to holdthe guide wire 170. The holder 172 may have a handle 172, a passage 195,and a tightening member, such as a screw 196, intersecting the passage195. The guide wire 170 may be clamped in place in the passage 195 bytightening the screw 196. The guide wire 170 may be attached to theholder 172 before or after the guide wire 170 is inserted into the body.In many cases, the guide wire 170 may be long enough for a surgeon toextend the distal end 194 of the guide wire 170 into the space 23between the adjacent spinous processes 24 and 26. However, in some casesa surgeon may have to extend the length of the guide wire 170 using anextension 174.

The extension 174 may be an elongated member (e.g., rod or bar) having adistal end 200 and a proximal end 202. The distal end 204 may have aengagement portion 204, which may be in the form of screw threads. Thedistal end 204 may have a reduced diameter as compared to the rest ofthe extension 174. The engagement portion 204 of the extension 174 maybe screwed into the counterbore 192 in the proximal portion 190 of theguide wire 170.

After the guide wire 170 is in place in the body, a dilator 176 may bepositioned over the guide wire 170 and/or extension 174 (if used), andmay be moved toward the spine by sliding the dilator 176 along the guidewire 170 and/or extension 174. As shown in FIG. 28, the dilator 176 maybe a hollow tubular structure with a passage 205 therethrough. Thedistal end 208 of the dilator 176 may have a tapered surface 206. As thetapered surface 206 of the dilator 176 moves toward and into the space23 between the spinous processes 22 and 24, the tapered end 206 maydilate the soft tissue. A pin 210 may extend into the passage 205 nearthe proximal end 212. As shown in FIG. 29, the dilator 176 may bepositioned and moved over the guide wire 170 and/or extension 174 untilthe pin 210 engages the proximal end 190 of the guide wire 170 and/orproximal end 202 of the extension 174. The length of the dilator 176 maybe correlated to the length of the guide wire 170 such that the pin 210on the dilator 176 may abutment the proximal end 190 of the guide wire170 to prevent movement of the dilator 176 once the tapered surface 206reaches the space 23 between the spinous processes 24 and 26. It shouldbe noted that one or more sequential dilators may be placed over thedilator 176 and may be used to dilate the opening through tissue fromthe skin to the vertebrae.

After the dilator 176 is positioned in the body, tubes 180 and 182 maybe positioned over the dilator 176. The tubes 180, 182 may be part of aset of tubes which differ in size (e.g., diameter/dimension) toaccommodate different patient anatomies. For example, thediameter/dimension of the tubes may be between about 0.1 inches andabout 1.0 inches, more preferably, between about 0.15 inches and about0.8 inches and, most preferably, between about 0.25 inches and about0.65 inches. The tube may be used to distract tissue as well as thespace in between the spinous processes of adjacent vertebrae. The tube180 of FIGS. 30-32 may have a configuration similar to the tube 182 ofFIGS. 33-35. Tube 180 may have a smaller diameter and may be shorterthan tube 182. All tubes in the set of tubes, including tubes 180, 182may be cylindrical and each tube with a larger diameter may be sized tofit closely over the tube with the next smallest diameter. In this way,all of the tubes in the set may be nested concentrically together. Inaddition, certain tubes may correspond to the different sized devices10. These tubes may be configured such that the tube has an innerdiameter closely matching the outer diameter D of the spinous spacer 10.Such a construction may enable a device 10 to slide closely and smoothlythrough its corresponding tube when the spinous spacer 10 is in theextended configuration of FIG. 2. The tubes may also have two slots 260which may enable retainers 14, 16, 18 and 20 to be deployed through thetube as described below. In other embodiment the tubes may have one slot260.

In use, the surgeon may first select a tube having a first dimension D1,such as, for example, the tube 180 shown in FIG. 30. Similar to othertubes, tube 180 may have a tapered distal end 220. The surgeon may movethe tube 180 over the guide wire 170 and/or dilator 176 (i.e., theassembly of FIG. 29) so that the tube 180 may move along the dilator 176toward the distal end 208 of the dilator 176. As the tapered distalportion 220 of the tube 180 is moved into the space 23 between thespinous processes 24 and 26, it may dilate the soft tissue as well asdistract the spinous processes 24 and 26. Further dilation anddistraction may be accomplished by moving successively largerdimensioned tubes over smaller tubes. This process may be repeated untildilation and distraction is completed by a final outermost tube such as,for example, tube 182 of FIG. 33 (i.e., dilation/distraction continuesuntil adjacent spinous processes are separated by a desired distance).In order to help properly position the tubes in between adjacentvertebrae, the tubes may have at least one pair of indication slots 266.The indication slots 266 may be spaced axially from the distal end 262of the tubes and may be diametrically opposed to each other. Whenlooking at the tubes 180, 182 from the view shown in FIGS. 30 and 33,the indication slots 266 may overlap each other and may be oriented atan angle with respect to each other. For example, the indication slots266 may be at a 90 degree angle to each other so that their overlappingx-ray image may form an “X” when the tube is viewed in the orientationshown in FIG. 30 or 33. Such a configuration may be used to produceshapes when viewing an x-rays. As shown in the embodiment of FIGS. 30and 33, another pair of indication slots 268 may be provided on tube180, 182 more proximal than slots 266. The pairs of indication slots 266and 268 may enable a surgeon to rotate the tube until the “X” images areformed in an x-ray view from the rear of the spine. Once the “X” imageis visible, this may indicate that the tube and, in particular, theslots 266 are correctly oriented for deployment of the retainers 14, 16,18 and 20 therethrough.

As seen in FIG. 33, each tube may have a knob 222 at its proximal end224 which may project inwardly in the passage through the tube. When alarger tube is placed over a smaller tube, the knob 222 on the largertube may move into abutment with the distal most end 224 of the smallertube. Such a construction may limit movement of larger tubes over smalltubes so that the tapered distal end 220 of the concentric tubes overlapat the same location between the spinous processes 24 and 26.

Each tube may also have a pair of slots 230 at its proximal end 224. Theslots 230 may delineate an opposed pair of sections 232, which may bedeflectable. The section 232 may be axially aligned with the knob 222but may be spaced a short distance axially from the knob 222. In orderto remove smaller tubes (e.g., tube 180) from the outermost tube 182, asurgeon may push the proximal end 224 at a location 224 a opposite theknob 222 (e.g., at a location approximately 180 degrees from the knob)in a direction towards the knob 222 (e.g., in a direction perpendicularto the longitudinal axis of the outermost tube 182). The slots 230 mayenable the proximal end 224 of the tube 182, including the knob 222 andsections 232, to be deflected upward as shown in FIG. 30 so that theconcentric inner tubes can be removed together from the outermost tube182. The guide wire 174 and the dilator 176 may also be removed from theoutermost tube 182. With the tube 182 positioned in between the spinousprocesses 24 and 26, the surgeon may select a device 10 of a sizecorresponding to the inner dimension of the outermost tube 182. Asurgeon may then attach the selected device 10 to the implant holder140, and may move the device 10 through the tube 182 towards and inbetween the spinous processes 24 and 26.

The implant holder 140 may be inserted into the tube 182 until theproximal most portion 224 of the outermost tube engages a steppedportion 250 (FIGS. 22 and 23) of the holder 140. The stepped portion 250may have dimensions so that each step matches the inner diameters of atube in the set of tubes (e.g., tubes 180, 182). Each step 250 may alsohave a notch 252 to receive the knob 222 on the corresponding tube. Sucha construction may assist in positioning the implant in the properlocation between adjacent spinous processes 24, 26 (i.e., the steppedportion 250 may act as a stop, which may prevent the device 10 frombeing inserted too far through the tube) as well as aligning theretainers 14, 16, 18 and 20 with the slots 260 (i.e., positioning theknob 222 in the notch 252 may prevent rotational misalignment).

Once the device 10 and holder 140 are in place (i.e., at the distal end220 of the tube 182), the actuation tool 184 shown in FIG. 36 (e.g.,screwdriver) may be inserted through the hollow shaft 146 on the holder140. Alternatively, the holder 140, actuation tool 184 and device 10 maybe attached together before placement in the body and inserted into thebody as a single unit. The tool 184 may be inserted through the holder140 until an engagement portion 254 of the tool 184 is received in therecess 105 of the connector 100. The tool 184 may then be rotated whilethe holder 140 is held in position. The tool 184 may cause the connector100 to rotate and the holder 140 may prevent rotational movement of theend portions 40, 42. In this way, the end portions 40, 42 may moveaxially along the axis 43 towards each other. As the end portions 40, 42move towards each other, the retainers 14, 16, 18 and 20 may be deployedfrom the body portion 12 and may be positioned around adjacent spinousprocesses 24, 26. It should be noted that the end portions 40, 42 maymove towards each other until the retainers 14, 16, 18 and 20 tightlygrip or firmly engage the spinous processes, thereby holding the device10 in place. The distance between the end portions 40, 42 when theretainers 14, 16, 18 and 20 are in the fully deployed position maydepend on the length L1 of the retainers 14, 16, 18 and 20 when at leasta portion of the retainers 14, 16, 18 and 20 engage the spinousprocesses. The length L1 of the retainers 14, 16, 18 and 20, in turn,may depend on the width W (FIG. 1) of the spinous processes.

The retainers 14, 16, 18 and 20 may be deployed from the body portion 12outwardly through the slots 260 of the tubes. The slots 260 may extendaxially from the distal most end 262 of each tube towards the proximalend 224. The slots 260 may be diametrically opposed to each other andmay be configured so that the tube 182 may be moved over the device 10(e.g., slide on and off the device 10) after the retainers 14, 16, 18and 20 have been deployed around the spinous processes. A pair of slots270 near the proximal end 224 of the tubes may serve as viewing windows,which may enable an operator to align the slots 260 (and thereby theretainers 14, 16, 18 and 20) in the cranio-caudal direction.

With the retainers 14, 16, 18 and 20 deployed and the device 10 inposition, the tool 184 may be withdrawn from the holder. The holder 140may be detached from the device 10 by rotating the wheel 148.Thereafter, the holder 140 may be withdrawn from the tube 182. The tube182 may then be removed from the patient, leaving the device 10 inbetween the adjacent spinous processes 24, 26.

As shown in FIG. 37, a removal tool 290 may be used to retract retainers14, 16, 18 and 20 into the body portion 12 and remove the device 10 fromthe body. The removal tool 280 may be a elongated member (e.g., rod)having a proximal end 292 and two distinct engagement portions 294 and296. The proximal portion 292 may be sized and configured for engagementwith a handle, drill or some other device which may impart rotationmotion. The first engagement portion 296 may have a screw thread 298 sothat the tool 290 may be inserted into the open outer end 132 (FIG. 21)of the end portion 64. The second engagement portion 294 may be sizedand configured (e.g., may have a polygonal or hex shape) to engage therecess 105 (FIG. 18) of the connector 100.

In order to remove the spinous spacer 10 from the spine, a surgeon mayuse a lateral approach to the spine. An incision may be made in the sideof a patient and the tool 290 may be inserted into the body until thesecond engagement portion 294 of the tool 290 may be inserted in therecess 105. The tool 290 may be used in place of the guide wire 170and/or the extension 174. A dilator 176 may be inserted over the tool290. Sequentially larger tubes 180, 182, etc. may be inserted overdilator 176 and into the space 23 between the adjacent spinous processes24 and 26. When dilation and distraction are completed by placement ofan outermost tube 182, the smaller tubes and/or dilator 176 may beremoved from the tube 182.

The tool 290 and the connector 100 may then be rotated to drive the endportions 40 and 42 of the body portion 12 axially away from each other.As the body portion 12 moves from the contracted configuration of FIG. 3to the expanded configuration of FIG. 2, the retainers 14, 16, 18 and 20may be drawn back into the body portion 12 from the deployed positionsto the retracted positions. As the end portion 42 moves axially towardthe adjacent end of the connector 100, the screw thread 298 of the firstengagement portion 296 may engage the internal screw thread 114 (FIGS. 7and 9) of the inner portion 66 of the end portion 42. Such aconfiguration may cause the tool 290 to engage the device 10 in a mannersimilar to attachment of the implant holder 140. The rod 290 may then beused to pull the spinous spacer 10 through the tube 182.

FIGS. 38-40 illustrate another embodiment of an implant for treatingspinal stenosis. The device 300 may be part of set of implants which mayhave different sizes to accommodate different anatomies. The bodyportions 302 may be configured for installation between a pair ofadjacent spinal processes 24 and 26 (FIG. 1) by use of the installationdevices described above. The body structure 302 may have first andsecond end portions 304 and 306, which may be centered on a longitudinalaxis 307. A sleeve 308 may be freely movable axially and rotationallybetween the two end portions 304 and 306 of the body portion 302.

The first end portion 304 may have a base 310, which may be generallydome-shaped. A stem 312 may project axially from the base 310. The stem312 may be any shape, for example, cylindrical. A first hinge 320 mayoperably connect a first retainer 322 to the base 310. The hinge 320 mayhave a pivotal axis 323, which may be perpendicular to the longitudinalaxis 307 of the body portion 302. First hinge 320 may comprise a pinabout which the first retainer 322 may pivot or rotate. A secondretainer 326 may be operably connected to the stem 312 by a second hinge328, which may have a pivotal axis 329 which may be parallel to thefirst pivotal axis 323. Second hinge 328 may comprise a pin about whichthe second retainer 326 may pivot or rotate. A third and fourth retainer340 and 342 may be operably connected to the base 310 and the stem 312,respectively, by a third and fourth hinge 344 and 346, respectively. Thehinges 344 and 346 may have axes 347 and 349, respectively, which may beparallel to each other.

The device 300 may have an internal connector (not shown) which may besubstantially similar to the connector 100 of the device 10.Accordingly, the connector of the implant 300 may have two sections withscrew threads in opposite directions and each section may engage an endportion 304 and 306. Rotation of the connector about axis 307 may resultin the end portions 304 moving axially toward each other. An opening 350in the first end portion 302 may provide access for an actuation tool(e.g. screwdriver) to engage the connector such that the body portion302 may be moved from the extended configuration of FIGS. 38 and 39 tothe contracted configuration of FIG. 40.

When the end portions 304 and 306 are moved axially together, the firstretainer 322 and the third retainer 340 may contact surface 352 of thesleeve 308, and the sleeve 308 as it moves will push the first and thirdretainers 322, 240 outwardly away from axis 307. Moreover, as the secondend portion 306 moves inward, the second retainer 326 and the fourthretainer 342 may move or be pushed against cam surfaces 354, which maybe positioned within openings 355 of the second end portion 306. In thisway, the retainers 326 and 342 may move outwardly from the axis 307. Theretainers 322, 326, 340 and 342 may thus be moved pivotally fromretracted positions to deployed positions such that the retainers 322,326, 340 and 342 may be positioned on opposite sides of the adjacentspinous processes 24 and 26. The sleeve 308 may be able to rotate and/ordeflect under forces applied from the spinous processes 24 and 26 in thesame manner as the sleeve 44 shown in FIG. 1.

FIG. 41 illustrates yet another embodiment of a device for treatingspinal stenosis. The device 400 may have a body portion 432 and upperretainers 402, 404 and lower retainers 406, 408. The body portion 432may have first and second end portions 410, 412 and a sleeve 450positioned therebetween. The upper retainers 402 and 404 may bepivotally connected by hinges 414 and 416, respectively, on the firstand second end portions 410 and 412. The hinges 414 and 416 may havepivotal axes 417 and 419, respectively, which may be parallel to eachother. The lower retainers 406 and 408 may be pivotally connected byhinges 424 and 426, respectively, on first and second end portions 410and 412. The hinges 424 and 426 may have pivotal axes 427 and 429 whichare parallel to each other and parallel to the pivotal axes 417 and 419.All four pivotal axes 417, 419, 427 and 429 may be perpendicular to thelongitudinal central axis 431 of the body portion 432.

A body portion 432 of a selected size may be installed between theadjacent spinous processes 24 and 26 (FIG. 1) using the installationdevices described above. Once in position, an actuation tool (e.g.,screwdriver) may be inserted through an access opening 440 in the firstend portion 410 to actuate a connector (not shown) within the bodyportion 432. Similar to the connector 100, the connector of FIG. 41 maybe rotated in order to draw the two end portions 410 and 412 axiallytogether. In an expanded configuration, the retainers 402, 404, 406 and408 may be positioned substantially parallel to the axis 431. As the twoend portions 410, 412 are drawn together, the retainers 402, 404, 406and 408 may be moved against surfaces 446 at the opposite ends of thesleeve 450. As shown in FIG. 41, this may cause the retainers 402, 404,406 and 408 to pivot from retracted positions to deployed positions inwhich the retainers 402, 404, 406 and 408 may extend outward from theaxis 431 and body portion 432. In the contracted configuration, theretainers 402, 404, 406 and 408 may deploy and hold the device 400within the space 23 between the adjacent spinous processes 24 and 26.Moreover, the sleeve 450 may be able to rotate and/or deflect relativeto the other parts of the device 400 (e.g., end portions 410, 412) underforces applied from the adjacent spinous processes 24 and 26.

FIGS. 42, 43 and 44 illustrate alternative embodiments of sleeves 44,308, and 450 described above. As shown in FIG. 42, sleeve 500 may havean inner and outer component 510 and 512. The outer component 512 mayhave end portions 514 and 516. A wall portion 518, which may becylindrical, may extend axially between the end portions 514 and 516.The inner component 510 may be captured axially and rotationally withinthe outer component 512. The inner component may consist of a wall,which also may be cylindrical, with a thickness which may besubstantially greater than the thickness of the surrounding wall portion518 of the outer component 512.

The inner component 510 of the sleeve 500 may be formed of a materialwith different properties than the material used to form the outercomponent 512. For example, the inner component 510 may be formed of amaterial with a lower modulus of elasticity than the outer component512. Using a more rigid material for the outer component 512, may resultin the sleeve 500 being more resistant to wear under the influence ofthe adjacent spinous processes 24 and 26 (FIG. 1). Moreover, making theinner component 510 of a softer material may enable the sleeve 500 to bemore flexible than if the sleeve 500 was formed entirely of a rigidmaterial, similar to the material which may be used to make the outercomponent 512. The inner and outer components 510, 512 may be made ofany suitable material, preferably biocompatible material, such as metal(e.g., stainless steel, titanium, aluminum, an alloy of two or moremetals), plastic, rubber, ceramic, natural body tissue (e.g., bone) or acomposite material (i.e., made up of two or more materials). In oneembodiment, the outer component 512 of the sleeve may be made ofpolycarbonate, which may have a higher modulus of elasticity thanpolycarbonate urethane which may be used to make inner component 510.

As shown in FIG. 43, the sleeve 502 may have a component 530 formed ofthe softer, more flexible material which may be contained entirelywithin the surrounding structure of the component 532. The component 532may be formed of the more rigid material than the material of component530. Furthermore, in the sleeve 504 of FIG. 44, the outer component 540may be made of a material which may have a lower modulus of elasticitythan the material of the inner component 542. The softer outer materialmay results in less wear to adjacent spinous processes 24 and 26positioned against the sleeve 504.

While the foregoing description and drawings represent the preferredembodiments of the present invention, it will be understood that variousadditions, modifications and substitutions may be made therein withoutdeparting from the spirit and scope of the present invention as definedin the accompanying claims. In particular, it will be clear to thoseskilled in the art that the present invention may be embodied in otherspecific forms, structures, arrangements, proportions, and with otherelements, materials, and components, without departing from the spiritor essential characteristics thereof. One skilled in the art willappreciate that the invention may be used with many modifications ofstructure, arrangement, proportions, materials, and components andotherwise, used in the practice of the invention, which are particularlyadapted to specific environments and operative requirements withoutdeparting from the principles of the present invention. In addition,features described herein may be used singularly or in combination withother features. The presently disclosed embodiments are therefore to beconsidered in all respects as illustrative and not restrictive, thescope of the invention being indicated by the appended claims, and notlimited to the foregoing description.

1. An apparatus insertable between spinous processes of two adjacentvertebrae through a lateral opening in a minimal invasive approach fortreating spinal stenosis, the apparatus comprising: an implant bodystructure configured to fit between the spinous processes; first,second, third and fourth retainers operably associated with the bodystructure; and a screw substantially located within the implant bodystructure, the screw operative to move the first, second, third andfourth retainers from a retracted position to a deployed position,wherein in the retracted position the first and second retainers arepositioned beside each other and generally inside the implant bodystructure and the third and fourth retainers are positioned beside eachother and generally inside the implant body structure, wherein in thedeployed position the first and third retainers extend outwardly fromthe implant body structure adjacent a first side of the spinousprocesses and the second and fourth retainers extend outwardly from theimplant body structure adjacent a second side of the spinous processes;wherein the screw includes a longitudinal axis and the body structurecomprises first and second body end portions spaced apart along theaxis; wherein rotation of the screw in a first direction moves the firstand second body end portions axially toward each other such that theretainers move from the retracted position to the deployed positionunder the influence of the first and second body end portions as theyare moved axially toward each other; and wherein each of the first,second, third and fourth retainers is a wire.
 2. An apparatus as definedin claim 1 wherein the screw is contained within the body structure. 3.An apparatus as defined in claim 1 wherein the first and third retainersare fixed to the first body end portion to move with the first bodyportion and the first and third retainers slide with respect to thesecond body end portion upon movement of the first body end portionaxially toward the second body end portion; wherein the first and secondbody portion is configured to deflect and guide the retainers to movethe retainers from the retracted position to the deployed position. 4.An apparatus as defined in claim 1 wherein the wires are generallyU-shaped having free ends, the free ends of the first and thirdretainers are fixed to the first body end portion to move with the firstbody end portion as the first body end portion moves axially relative tothe second body end portion and the free ends of the second and fourthretainers are fixed to the second body end portion to move with thesecond body end portion as the second body end portion moves axiallyrelative to the first body end portion.
 5. An apparatus as defined inclaim 4 wherein the first body end portion and second body end portioneach have a cam surface for deflecting the wires.
 6. An apparatus asdefined in claim 1 wherein the screw is further operative to retract theretainers from the deployed positions to the retracted positions.
 7. Anapparatus insertable between spinous processes of two adjacent vertebraethrough a lateral opening in a minimal invasive approach for treatingspinal stenosis, the apparatus comprising: an implant body structureconfigured to fit between the spinous processes; first, second, thirdand fourth retainers operably associated with the body structure; and ascrew substantially located within the implant body structure, the screwoperative to move the first, second, third and fourth retainers from aretracted position to a deployed position, wherein in the retractedposition the first and second retainers are positioned beside each otherand generally inside the implant body structure and the third and fourthretainers are positioned beside each other and generally inside theimplant body structure, wherein in the deployed position the first andthird retainers extend outwardly from the implant body structureadjacent a first side of the spinous processes and the second and fourthretainers extend outwardly from the implant body structure adjacent asecond side of the spinous processes; wherein the screw includes alongitudinal axis and the body structure comprises first and second bodyend portions spaced apart along the axis; wherein rotation of the screwin a first direction moves the first and second body end portionsaxially toward each other such that the retainers move from theretracted position to the deployed position under the influence of thefirst and second body end portions as they are moved axially toward eachother; and wherein the screw includes a screw thread in a firstdirection engaged with the first body end portion, and an oppositelyextending screw thread in a second direction engaged with the secondbody end portion.
 8. An apparatus insertable between spinous processesof two adjacent vertebrae through a lateral opening in a minimalinvasive approach for treating spinal stenosis, the apparatuscomprising: an implant body structure configured to fit between thespinous processes; first, second, third and fourth retainers operablyassociated with the body structure; and a screw substantially locatedwithin the implant body structure, the screw operative to move thefirst, second, third and fourth retainers from a retracted position to adeployed position, wherein in the retracted position the first andsecond retainers are positioned beside each other and generally insidethe implant body structure and the third and fourth retainers arepositioned beside each other and generally inside the implant bodystructure, wherein in the deployed position the first and thirdretainers extend outwardly from the implant body structure adjacent afirst side of the spinous processes and the second and fourth retainersextend outwardly from the implant body structure adjacent a second sideof the spinous processes; wherein the screw includes a longitudinal axisand the body structure comprises first and second body end portionsspaced apart along the axis; wherein rotation of the screw in a firstdirection moves the first and second body end portions axially towardeach other such that the retainers move from the retracted position tothe deployed position under the influence of the first and second bodyend portions as they are moved axially toward each other; and whereinthe body structure further includes a sleeve located axially between thefirst and second body end portions.
 9. An apparatus as defined in claim8 wherein the sleeve is capable of rotating relative to the first andsecond body end portions under forces applied from the spinous processesof the two adjacent vertebrae.
 10. An apparatus as defined in claim 8wherein the sleeve is capable of deflecting under forces applied fromthe spinous processes of the two adjacent vertebrae.
 11. An apparatus asdefined in claim 10 wherein the sleeve has opposite end sections and acentral section that is thinner than the opposite end sections.
 12. Anapparatus as defined in claim 10 wherein the sleeve has a first sleevecomponent formed of a material with a modulus of elasticity and a secondsleeve component formed of a material with a different modulus ofelasticity.
 13. An apparatus insertable between spinous processes of twoadjacent vertebrae through a lateral opening in a minimal invasiveapproach for treating spinal stenosis, the apparatus comprising: animplant body structure configured to fit between the spinous processes;first, second, third and fourth retainers operably associated with thebody structure; and a screw substantially located within the implantbody structure, the screw operative to move the first, second, third andfourth retainers from a retracted position to a deployed position,wherein in the retracted position the first and second retainers arepositioned beside each other and generally inside the implant bodystructure and the third and fourth retainers are positioned beside eachother and generally inside the implant body structure, wherein in thedeployed position the first and third retainers extend outwardly fromthe implant body structure adjacent a first side of the spinousprocesses and the second and fourth retainers extend outwardly from theimplant body structure adjacent a second side of the spinous processes;wherein the body structure comprises a first end portion and a secondend portion, the screw includes a longitudinal axis, at least a portionof the screw having external screw threads, the screw configured forrotation; wherein the first end portion and second end portion each haveinternal threads and are mounted on the screw and each retainercomprises a generally U-shaped wire having two free ends; wherein thetwo free ends of the first and third retainers are fixed to the firstend portion and the two free ends of the second and fourth retainers arefixed to the second end portion; wherein, upon rotation of the screw ina first direction, the first and second end portions move axially alongthe screw closer together and deploy the retainers at an angle withrespect to the axis of the screw.
 14. An apparatus insertable betweenspinous processes of two adjacent vertebrae through a lateral opening ina minimal invasive approach for treating spinal stenosis, the apparatuscomprising: an implant body structure having a longitudinal axis andconfigured to be placed between the spinous processes, the bodystructure including first and second body end portions spaced apartalong the axis; first, second, third and fourth retainers operablyassociated with the body structure; and a mechanism located within theimplant body structure, the mechanism operative to move the first,second, third and fourth retainers from a retracted position, whereinthe retainers are generally aligned with the axis, to a deployedposition, wherein the first and third retainers extend at an angle withrespect to the axis and beside a first side of the spinous processes andthe second and fourth retainers extend at an angle with respect to theaxis and beside a second side of the spinous processes, whereinactivation of the mechanism in a first direction moves the first andsecond body end portions axially toward each other such that theretainers move from the retracted position to the deployed positionunder the influence of the first and second body end portions as theyare moved axially toward each other, the first and third retainers beingcoupled to the first body end portion so that the first and thirdretainers move with the first body portion, and the first and thirdretainers are slidable with respect to the second body end portion uponmovement of the first body end portion axially toward the second bodyend portion so that the second body portion deflects and guides thefirst and third retainers from the retracted position to the deployedposition; and the second and fourth retainers are coupled to the secondbody end portion so that the second and fourth retainers move with thesecond body portion, and the second and fourth retainers are slidablewith respect to the first body end portion upon movement of the secondbody end portion axially toward the first body end portion so that thefirst body portion deflects and guides the second and fourth retainersfrom the retracted position to the deployed position.
 15. An apparatusas defined in claim 14 wherein the mechanism comprises an axiallyextending connector in screw-threaded engagement with the first andsecond body end portions.
 16. An apparatus as defined in claim 14wherein the body structure further includes a sleeve located axiallybetween the first and second body end portions.
 17. An apparatus asdefined in claim 16 wherein the sleeve is configured to rotate relativeto the first and second body end portions under forces applied from thespinous processes.